Steam shortcuts, Discord RPC, MangoHud

[loathingKernel]

Rare

• Download wide images too during cover art download. These can be used when exporting to Steam as backgrounds
• Possibly fix a segmentation fault that happens when doing too many parallel cover art downloads.
• Fix Discord RPC not updating to show the currently running game when a game was started
• Implement some initial code to export games to Steam as Non-Steam games
• Fix library filter reverting to the default on start
• Add fps_limit, vsync and gl_vsync option for MangoHud
• Add drop-down menu option to add a game from Rare to Steam as a Non-Steam game.
• Improve library sorting

RareLauncher

• Check if dry-running before doing anything else
• Always show console when running detached games to inform the user about it.
• Detach the pre-launch command if we don't have to wait for it to finish